Low molecular weight polymers with narrow poly dispersity index (1&lt;1.7) find applications as additives in petroleum industry for pour point depression, viscosity improvement, and enhancement of antioxidant properties. These are commonly prepared by condensation, solution or charge transfer polymerizations.
Condensation Polymerization follows a step growth mechanism which involves the same basic reaction either between two monomeric units, between two end groups of different polymer chains, or between a monomeric group and end group of a polymer chain. However, the utility of this type of process is limited to monomers containing specific functional groups such as carboxylic and phenolic groups.
In solution polymerization process a solvent is used to dissolve the monomers, polymer and the initiators, and the solvent directly interacts with the growing chain to enable formation of low mocelular weight polymers. The main disadvantage of this process is that it should be conducted at relatively high temperatures (&gt;70.degree. C.) to be able to initiate the reaction. In charge transfer (CT) polymerization also a solvent is used to dissolve the monomers, polymer and the initiators. However, unlike in case of solution polmerization process, the initiation mechanism in CT polymerization takes place even at ambient temperatures(.ltoreq.25.degree. C.) through electron donor-acceptor interactions. Because of this distinct advantage CT polymerization route was chosen in the present case.